The proposal is aimed at the continuation of the chemical and biological studies of human chorionic gonadotropin (hCG) and other gonadotropins. The structural studies will involve the elucidation of the fine details of the carbohydrate structure of hCG and the placement of disulfide bonds. In addition, studies on the structures of the disease state hCG, pregnant mare serum gonadotropin, and equine follicle stimulating hormone will be undertaken. Structure and function studies, particularly by the modification of hCG in the protein and carbohydrate parts, will be continued with a view to developing inhibitors of hCG action at the target site. Large scale purification and characterization of the bovine corpus luteal plasma membrane hCG/LH receptor will be undertaken. Studies on the reconstitution of the receptor in liposomes and their subsequent incorporation in thymocytes and adrenal cells will be continued. Ability of the hormone to stimulate cAMP and steroidogenesis in these receptor containing nontarget cells will be measured. Finally, efforts to obtain specific antigen(s) by chemical and enzymatic modification of hCG-beta will be continued. The specific antigen will be utilized for setting up a specific radioimmunoassay for hCG and also in the development of a human contraceptive vaccine. For contraceptive vaccine, initial testing of the antigens will be done in rhesus monkeys, langur monkeys and hamsters. Toxicology of the antigens of hCG-beta will be tested in guinea pigs, rabbits and monkeys.